process for manufacturing a sweetener and use thereof

ABSTRACT

Highly purified Stevioside and Rebaudioside A were prepared from sweet glycoside extracts obtained from  Stevia rebaudiana  Bertoni leaves. The resulting sweeteners are suitable as non-calorie, non-cariogenic, non-bitter, non-lingering sweeteners, which may be advantageously applied in foods, beverages, and milk products.

RELATED APPLICATIONS

This application is a continuation-in-part application of U.S. patentapplication Ser. No. 11/246,152, filed Oct. 11, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a process for producing a highlypurified Stevioside and Rebaudioside A from the extract of the Steviarebaudiana Bertoni plant and use thereof in various food products andbeverages.

2. Description of the Related Art

In view of food sanitation, the use of artificial sweeteners such asdulcin, sodium cyclamate and saccharin has been restricted. Howevernatural sweeteners have been receiving increasing demand. Steviarebaudiana Bertoni is a plant that produces an alternative sweetenerthat has an added advantage of being a natural plant product. Inaddition, the sweet steviol glycosides have functional and sensoryproperties superior to those of many high potency sweeteners.

The extract of Stevia rebaudiana plant contains a mixture of differentsweet diterpene glycosides, which have a single base—steviol and differby the presence of carbohydrate residues at positions C13 and C19. Theseglycosides accumulate in Stevia leaves and compose approximately 10%-20%of the total dry weight. Typically, on a dry weight basis, the fourmajor glycosides found in the leaves of Stevia are Dulcoside A (0.3%),Rebaudioside C (0.6%), Rebaudioside A (3.8%) and Stevioside (9.1%).Other glycosides identified in Stevia extract include Rebaudioside B, C,D, E, and F, Steviolbioside and Rubusoside.

The physical and sensory properties are well studied only for Steviosideand Rebaudioside A. They were tested for stability in carbonatedbeverages and found to be both heat and pH stable (Chang and Cook,1983). The sweetness potency of Stevioside is around 210 times higherthan sucrose, Rebaudioside A in between 200 and 400 times, andRebaudioside C and Dulcoside A around 30 times (Phillips, 1989 andTanaka, 1997).

However, apart from its high level of sweetness, they have alsointrinsic properties of post-bitter taste and unpleasant and undesirableaftertaste. Some undesirable taste characteristics of glycosides can beas a result of contamination of other substances, presented in extract.

One of the main ways to improve the taste quality is the enzymaticglycosylation of mixture of semi-purified steviol glycosides. Anotherway to produce highly purified individual glycosides with standardcharacteristics and minimal content of accompanying compounds.

The invention related to the purification of two mainglycosides—Stevioside and Rebaudioside A and use thereof.

A process for the recovery of diterpene glycosides, including Steviosidefrom the Stevia rebaudiana plant is described (U.S. Pat. No. 4,361,697).A variety of solvents, having different polarities, were used in asequential treatment that concluded with a high performance liquidchromatographic (HPLC) separation procedure.

A method for the recovery of Rebaudioside A from the leaves of Steviarebaudiana plants has been developed (U.S. Pat. No. 4,082,858). Again,final purification is achieved by liquid chromatography subsequent to aninitial extraction with water and an alkanol having from 1 to 3 carboncarbons, preferably methanol. It is also known that water may be used asthe initial solvent; their preferred solvent at this stage is a liquidhaloalkane having from 1 to 4 carbon atoms. The preferred second solventis an alkanol having from 1 to 3 carbon atoms, while the preferred thirdsolvent is an alkanol having from 1 to 4 carbon atoms and optionallyminor amounts of water.

Individual sweet glycosides can be obtained from the Stevia rebaudianaplant. A mixture of sweet glycosides extracted from the Steviarebaudiana plant is processed to remove impurities by using two types ofion-exchangers. After removing the mixed sweet glycosides from thesecond column with methanol, the solution is dried. Upon refluxing thedried solids in a methanol solution and then cooling the solution,Stevioside precipitates out. The filtrate is further concentrated andcooled to precipitate out Rebaudioside A. This Rebaudioside A can befurther purified as can the previously obtained Stevioside (U.S. Pat.No. 5,962,678). However, a large amount of toxic organic solvent, suchas methanol is used.

However, all the above-mentioned methods allow the production ofStevioside and Rebaudioside A not in highly purified grade, whichfurther possess a residual bitterness and aftertaste.

On the other hand, the unfavorable taste of the glycosides can be as aresult of contamination of impurities, presented in extract. Highlypurified Stevioside and Rebaudioside A possessing an improved tasteprofile and there is a need to provide an easy and commercially valuableprocess for the manufacturing the highly purified Stevioside andRebaudioside A, and use thereof in various beverages and food products.

SUMMARY OF INVENTION

An object of the present invention is to provide a commercially valuableprocess for producing a highly purified sweetener from the extract ofStevia rebaudiana Bertoni plant and use thereof in various food productsand beverages, which overcomes the disadvantages of the related art.

The invention, in part, pertains to the dried and powdered leaves beingsubjected to water extraction and the resulted extracts is purifiedusing treatment with a base such as calcium hydroxide and then ironchloride. The filtrate was deionized on, e.g., Amberlite FPC23H,Amberlite FPA51, and Amberlite FPA98Cl. The filtrate is concentratedunder vacuum and spray dried. The isolation and purification ofStevioside and Rebaudioside A were developed using alcoholicprecipitation and ultrafiltration. The highly purified Stevioside andRebaudioside A were obtained. Any type of existing Stevia extract withvarious ratio of sweet glycosides are feasible.

The highly purified glycosides were applied in various foods andbeverages as sweetener.

The invention, in part, pertains to a purified sweet glycosides extractproduced from the Stevia rebaudiana plant, wherein the main sweetglycosides are Rebaudioside A and Stevioside, obtained by a processincluding drying Stevia rebaudiana leaves, treating the leaves toextract an aqueous liquid solution containing mixed sweet glycosides,extracting the Stevia rebaudiana leaves, obtaining an extract, filteringthe extract, obtaining a filtrate, treating the filtrate with a basesuch as calcium hydroxide, treating the extract with trivalent ironchloride, desalting, decolorizing, and evaporating the filtrate todryness.

In the invention, purified Rebaudioside A and Stevioside can be obtainedby dissolving sweet glycosides in methanol at ambient temperatures toprecipitate Stevioside, filtering the solution to recover a precipitateof Stevioside, purifying, recovering a high purity Stevioside,concentrating the remaining solution and evaporating to dryness,suspending the powder in ethanol, heating and then cooling the solutionto precipitate Rebaudioside A. Suspending the crystalline Rebaudioside Aobtained in ethanol-water solution at cool conditions (10-12° C.)prepares a high purity of Rebaudioside A. Stevioside or Rebaudioside Ahas a purity of at least 98%. Applications are found in various foodssuch as chocolate, ice cream, beverage, dairy products, as a sweetenerin a tablet form.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention. The drawings illustrate embodiments ofthe invention and together with the description serve to explain theprinciples of the embodiments of the invention.

FIG. 1 shows a sensory evaluation of raw Stevia extract, Stevioside, andRebaudioside A;

FIG. 2 shows a sensory evaluation of Stevioside with a different gradeof purity; and

FIG. 3 shows a sensory evaluation of Rebaudioside A with a differentgrade of purity;

DETAILED DESCRIPTION

Advantages of the present invention will become more apparent from thedetailed description given hereinafter. However, it should be understoodthat the detailed description and specific examples, while indicatingpreferred embodiments of the invention, are given by way of illustrationonly, since various changes and modifications within the spirit andscope of the invention will become apparent to those skilled in the artfrom this detailed description.

The dried leaves of Stevia rebaudiana Bertoni were extracted by 10volumes of water. The proportion of extraction water preferably wasabout 5 liters to about 15 liters (pH 6.0 to 7.0) to one kilogram ofleaves. Greater volumes of solvent can be used, however, it was notpreferable from the practical standpoint. The duration of extraction maybe from 0.5 hours to 24 hours, with a period of from about 1 hours toabout 6 hours preferred.

The extraction temperature can be in the limits of 25-90° C., howeverthe temperatures between 45-75° C. are more preferable.

The plant material was separated from the solution by filtration, andthe pH of the filtrate was adjusted to about 10 with calcium hydroxideand heated between 40-60° C., preferably from 50° C. to 55° C., forabout 0.5-1.0 hours, cooled to ambient temperature with slow agitation,and neutralized by FeCl₃. After mixing for 10-15 minutes, theprecipitate was removed by filtration; the filtrate was passed throughthe Celite, deionized, and decolorized by Amberlite FPC23H, AmberliteFPA51, and Amberlite FPA98Cl by conventional manner. The solution wasconcentrated and spray dried.

The yellow powder had a content of 3.4% Dulcoside, 64.6% Stevioside,6.7% Rebaudioside C and 25.3% Rebaudioside A.

An HPLC analysis of the obtained product was carried out using anAgilent Technologies 1100 Series (USA) equipped with Zorbax-NH₂ columnusing acetonitrile-water gradient from 80:20, v/v (2 minutes) to 50:50,v/v during 70 minutes and UV detector at 210 nm.

The obtained powder was dissolved in methanol and maintained at atemperatures 20-50° C., preferably at 20-25° C., for 0.5-6.0 hours,preferably 0.5-1.0 hours with agitation. The proportion of extract andmethanol was between 1:2-1:7, w/v, preferably 1:5. During this time theprecipitate was formed, which was filtered and dried. According to theHPLC analysis, the powder contents were around 90-91% of Stevioside. Asecond treatment by methanol was not efficient to prepare high purityStevioside.

For the further purification, the powder was mixed with two volumes of90% of ethanol and at 10-12° C. and maintained for about 30 minutes withslow agitation. The precipitate was separated by filtration and driedunder vacuum. The Stevioside with about 98.5-99.4% purity was obtained.

The filtrates were combined and used for recovery of Rebaudioside A. Forthis purpose the remaining solution was evaporated to remove themethanol, the syrup obtained diluted with water and passed throughpolysulfone based ultrafiltration membranes (with a filteringdiscrimination of 2.5 kDa) (Liumar Technologies, Ottawa, Canada) withdiafiltration. The filtrate was concentrated and spray dried. Theobtained powder was mixed with 96.2% ethanol and maintained at 45-50° C.for about 30 minutes with agitation. The proportion of syrup and ethanolwas between 1:2-1:7, w/v, preferably 1:5. During this time theprecipitate was formed, which was filtered and dried. Rebaudioside Awith 88-90% purity was obtained. For the further purification the powderwas mixed with two volumes of 92% ethanol and maintained at 10-12° C.for about 60 minutes with slow agitation. The crystals were filtered anddried. Rebaudioside A with 98.9% purity was obtained.

Based on the results of preliminary test on the sweetening power of thesweeteners, aqueous solutions of commercial Sievia extract (0.05%)commercialized by Ganzhou Julong High-Tech Food Industry Co., Ltd(China), Stevioside (0.07%), and Rebaudioside A (0.028%) were prepared.

The organoleptic test was carried out with 30 previously trained panelmembers. It was observed that Rebaudioside A has the highest sweetnesslevel (5.96), followed by Stevioside with a mean score of 4.62, andcommercial Stevia extract had the lowest mean score of 2.96.Rebaudioside A had the lowest score for bitterness (1.76), andcommercial Stevia extract was the most bitter compared to the othersamples. For overall acceptability, Rebaudioside A had the highest scoreof 4.05 followed by Stevioside (3.81) and raw extract (3.16) (FIG. 1).

The taste profile of Stevioside with 99.3% of purity was more preferableas compared with 90.2 and 95.4% (FIG. 2). The similar feature wasobtained for Rebaudioside A with various grades of purity (FIG. 3).

The highly purified sweeteners can be favorably used for seasoningvarious food products (for instance, soy sauce, soy sauce powder, soypaste, soy paste powder, dressings, mayonnaise, vinegar, powderedvinegar, bakery products and confectioneries, frozen-desserts, meatproducts, fish-meat products, potato salad, bottled and canned foods,fruit and vegetables) in intact or mixed forms with other sweeteners,such as corn syrup, glucose, maltose, sucrose, lactose, aspartame,saccharin, sugar alcohols, organic and amino acids, flavors and/orcoloring agents.

The products are favorably usable as a low-cariogenic and low-caloriesweetener because it is less fermentable by oral dental-caries causativemicroorganisms. Exemplary applications include low-cariogenic foodproducts such as confectioneries including chewing gum, chocolate,biscuits, cookies, toffee and candy. Additionally applications includesoft drinks such as coffee, cocoa, juice, carbonated drinks, sour milkbeverage, yoghurt drinks and alcoholic drinks, such as brandy, whisky,vodka and wine. In addition to the above-described uses, the sweetenersare usable for sweetening drugs and cosmetics.

The following examples illustrate preferred embodiments of theinvention.

Example 1 Extraction of Sweet Glycosides

The leaves of Stevia rebaudiana are dried at 55° C. for three hours in avacuum oven and powdered (30 mesh). One kg of the obtained material wasmixed with 10 liters of water (pH 6.5) and heated to 55° C. with slowagitation for 10 hours. The plant material was separated from thesolution by filtration and the pH of the filtrate was adjusted to 10with about 24 grams of calcium hydroxide and heated to 50° C. for 0.5hours. The obtained mixture was cooled to ambient temperature and the pHwas adjusted to about 7.0 by about 53 grams of FeCl₃. After mixing for15 minutes the precipitate was removed by filtration.

The slightly yellow filtrate was passed through the Celite, deionized,and decolorized by conventional manner on Amberlite FPC23H, AmberliteFPA51, and Amberlite FPA98Cl commercialized by ROHM & HAAS Co., Germany.The solution was concentrated and spray dried. The yield was 122 gramsof powder with a content of sweet glycosides to about 91%. The mixturecontains 3.4% Dulcoside, 64.6% Stevioside, 6.7% Rebaudioside C and 25.3%Rebaudioside A.

Example 2 Preparation of Stevioside

100 grains (on the base of dry material) of the powder obtained by theprocess of EXAMPLE 1 was mixed with 0.5 liters of methanol andmaintained at 25° C. for 45 minutes with slow agitation. The precipitateStevioside was filtered and dried. 61.2 grams of Stevioside with 90.6%purity was obtained.

For the further purification the powder was mixed with two parts of 90%of ethanol, and maintained at 10-12° C. for about 30 minutes with slowagitation. The precipitate was separated by filtration and dried undervacuum. The product weighed 58.8 grams and contained 99.3% Stevioside.

Example 3 Preparation of Rebaudioside A

The remaining solutions after separation of Stevioside (EXAMPLE 2) werecombined, and methanol was removed by evaporation. The syrup was dilutedwith water and passed through polysulfone based ultrafiltrationmembranes (with a filtering discrimination of 2.5 kDa) (LiumarTechnologies, Ottawa, Canada) with diafiltration. The filtrate wasconcentrated and spray dried. 40.8 grams of powder with content ofRebaudioside A of around 60% were obtained. The powder was mixed withfive volumes (w/v) of 96.2% ethanol and maintained at 50° C. for 30minutes with slow agitation. The precipitate was filtered and dried.Rebaudioside A with 89.8% purity was obtained. The powder was mixed withtwo volumes of 92% of ethanol and maintained at 12° C. for 60 minuteswith slow agitation. The crystals were filtered and dried. 23.6 grams ofRebaudioside A of 98.9% purity was obtained.

Example 4 Low-Calorie Orange Juice Drink

Orange concentrate (35%), citric acid (0.38%), ascorbic acid (0.05%),sodium benzoate (0.02%), orange red color (0.01%), orange flavor(0.20%), and sweetener (0.06%) containing 90.2, 95.4 or 99.3% ofStevioside, or 80, 90, or 98.9% of Rebaudioside A were blended anddissolved completely in the water (up to 100%) and pasteurized. Thesensory evaluation of the samples is summarized in the TABLE 1. The datashows that best results were obtained for highly purified Rebaudioside Aand Stevioside.

TABLE 1 Comments Sample Flavor Aftertaste Mouth feel Stevioside - Sweetand balanced flavor Slight bitterness in Acceptable 90.2% aftertasteStevioside - Sweet and balanced flavor Slight bitterness in Acceptable95.4% aftertaste Stevioside - Sweet, pleasant, balanced flavor Clean, nobitterness Quite full 99.3% Rebaudioside Sweet, rounded and balancedAlmost no any Acceptable A - 80.0% flavor bitterness Rebaudioside Sweet,rounded and balanced Almost no any Full A - 90.0% flavor bitternessRebaudioside High quality of sweetness, Clean, no unpleasant Quite fullA - 98.9% pleasant, taste similar to aftertaste sucrose, balanced flavor

By the same way can be prepared juices from other fruits, such as apple,lemon, apricot, cherry, pineapple, etc.

Example 5 Low-Calorie Carbonated Lemon-Flavored Beverage

The formula for the beverage was as below:

Ingredients Quantity, kg Sugar 30.0 Sweetener 0.4 Citric acid 2.5 Greentea extract 25.0 Salt 0.3 Lemon tincture 10.0 L Juniper tincture 8.0 LSodium benzoate 0.17 Carbonated water up to 1000 L

Sensory and physicochemical characteristics of the drink are presentedin the TABLE 2.

The drinks with highly purified Rebaudioside A and Stevioside weresuperior with an excellent flavor and taste.

TABLE 2 Characteristics Stevioside - Rebaudioside Rebaudioside ItemStevioside - 90.2% 99.3% A - 90.0% A - 98.9% Appearance Transparentliquid, Transparent Transparent Transparent free of sediment liquid,free of liquid, free of liquid, free of and strange sediment andsediment and sediment and impurities. A light strange strange strangeopalescence, caused impurities. A impurities. A impurities. A byfeatures of used light light light raw materials is opalescence,opalescence, opalescence, possible. caused by caused by caused byfeatures of features of features of used raw used raw used raw materialsis materials is materials is possible. possible. possible. Color Fromlight yellow up to From light From light From light yellow yellow up toyellow up to yellow up to yellow yellow yellow Taste Sour-sweet, someSour-sweet, Sour-sweet, Sour-sweet, bitterness in expression of almostno any expression of aftertaste sweetness is bitterness, sweetness israpid. The expression of rapid. taste is sweetness is satisfactory.rapid.

Example 6 Low-Calorie Carbonated Drink

The formula for the beverage was as below:

Ingredients Quantity, % Cola flavor 0.340 Phosphoric acid (85%) 0.100Sodium citrate 0.310 Sodium benzoate 0.018 Citric acid 0.018 Sweetener0.030 Carbonated water to 100

The beverages prepared with different sweeteners were given to 10 judgesfor comparison.

TABLE 3 shows the results.

TABLE 3 Number of panelists Comparison Stevioside - Stevioside -Rebaudioside A Rebaudioside A Point 90.2% 99.3% 90.0% 98.9% Bitter taste6 2 3 0 Astringent taste 6 2 3 0 Aftertaste 6 2 3 0 Quality of Sweet,Clean (7 of the Sweet, some Clean (10 of the sweet taste bitterness in10 judges) bitterness in 10 judges) aftertaste (6 of aftertaste (5 ofthe 10 judges) the 10 judges) Overall Satisfactory (5 Satisfactory (8Satisfactory (8 Satisfactory (10 evaluation of the 10 of the 10 of the10 of the 10 judges) judges) judges) judges)

The above results show that the beverages prepared using highly purifiedStevioside and Rebaudioside A possessing good organolepticcharacteristics.

Example 7 Chocolate

A composition containing 30 kg of cacao liquor, 11.5 kg of cacao butter,14 kg of milk powder, 44 kg of sorbitol, 0.1 kg of salt, and 0.1 kg ofsweetener prepared according to the EXAMPLES 2 or 3, was kneadedsufficiently, and the mixture was then placed in a refiner to reduce itsparticle size for 24 hours. Thereafter, the content was transferred intoa conche, 300 grams of lecithin was added, and the composition waskneaded at 50° C. for 48 hours. Then, the content was placed in ashaping apparatus, and solidified.

The products are low-cariogenic and low-calorie chocolate with excellenttexture. Also, the organoleptic test carried out with 20 panelistsrevealed no lingering after-taste. The most desirable ones were theproducts with Rebaudioside-98.9% (19 members) and Stevioside 99.3% (16members).

Example 8 Ice-Cream

1.50 kg of whole milk were heated to 45° C., and 300 grams of milkcream, 100 grams of tagatose, 90 grams of sorbitol, 6 grams ofcarrageenan as a stabilizer, 3 grams of polysorbate-80 as an emulsifier,and 1.0 gram of sweetener prepared according to the EXAMPLES 2 or 3,were added into the milk and was stirred until the ingredientscompletely dissolved. The mixture then was pasteurized at a temperatureof 80° C. for 25 seconds. The homogenization of the obtained mixture wascarried out at a pressure of 800 bars and the samples were kept at atemperature of 4° C. for 24 hours to complete the aging process. Vanillaflavor (1.0% of the mixture weight) and coloring (0.025% of the mixtureweight) are added into the mixture after aging. The mixture was thentransferred to ice cream maker to produce ice cream automatically.Samples of ice creams produced were transferred to seal containers andwere kept in the freezer at a temperature of ±18° C.

The application of sweeteners does not affect the physicochemicalproperties of ice cream, as well as the overall attributes of color,smoothness, surface texture, air cell, vanilla aroma intensity, vanillataste, chalkiness, iciness and melting rate. Organoleptic test carriedout with 20 panelists. The most desirable ones were the products with98.9% Rebaudioside A (18 members) and 99.3% Stevioside (14 members).

Example 9 Yoghurt

In 5 kg of defatted milk, 4.0 grams of sweetener, prepared according toEXAMPLES 2 and 3, were dissolved. After pasteurizing at 82° C. for 20minutes, the milk was cooled to 40° C. A starter in amount of 150 gramswas added and the mixture was incubated at 37° C. for 6 hours. Then, thefermented mass was maintained at 10-15° C. for 12 hours.

The product is a low-calorie and low-cariogenic yoghurt without foreigntaste and odor.

Example 10 Table Top Tablet

A mixture, consisting of 58.5% lactose, 10% calcium silicate, 5%cross-carmellose, 5% L-leucine, 1% aerosol 200, 0.5% magnesium stearate,and 20% of a sweetener, obtained according to the EXAMPLE 2 or 3, waskneaded sufficiently. Then the mixture was shaped with the use of atabletting machine, equipped with punchers of 6.2 mm diameter, intotablets of 70 mg each, 3.0 mm thick, and 10±1 kg hardness

The tablets can be easily administrated due to their appropriatesweetness. However, the formulations using low grade of Stevioside andRebaudioside A were somewhat sticky with solubility about 3-4 minutes inwater at 25° C. The tablets, prepared with highly purified RebaudiosideA show the best characteristics with the solubility around 20-30seconds.

Example 11 Tooth Paste

A tooth paste was prepared by kneading a composition comprising ofcalcium phosphate, 45.0%; carboxymethylcellulose, 1.5%; carrageenan,0.5%; glycerol, 18.0%; polyoxyethylene sorbitan mono-ester, 2.0%;beta-cyclodextrin, 1.5%; sodium laurylsarcosinate, 0.2%; flavoring,1.0%; preservative, 0.1%; Rebaudioside A or Stevioside, obtainedaccording to the EXAMPLE 2 or 3, 0.2%; and water to 100%, by usual way.The product possesses good foaming and cleaning abilities withappropriate sweetness.

Example 12 Soy Sauce

0.8 g of Rebaudioside A/Stevioside mixture (1:1, w/w) obtained accordingto the invention was added to 1000 mL of soy sauce and mixedhomogenously. The products had an excellent taste and texture.

Example 13 Bread

1 kg of wheat flour, 37.38 grams of fructooligosaccharide syrup, 80grams of margarine, 20 grams of salt, 20 grams of yeasts, and 0.25 gramsof high purity Rebaudioside A or Stevioside, obtained according to theEXAMPLE 2 or 3 were placed into the blender and mixed well. 600 ml ofwater was poured into the mixture and kneaded sufficiently. At thecompletion of the kneading process, the dough was shaped and raised for30 to 45 minutes. The ready dough was placed in oven and baked for 45minutes. Bread samples had creamy white color, and smooth texture.

Example 14 Diet Cookies

Flour (50.0%), margarine (30.0%), fructose (10.0%), maltitol (8.0%),whole milk (1.0%), salt (0.2%), baking powder (0.15%), vanillin (0.1%),Rebaudioside A or Stevioside (0.55%), obtained according to thisinvention were kneaded well in dough-mixing machine. After molding ofthe dough the cookies were baked at 200° C. for 15 minutes.

The product is a low-calorie diet cookie with excellent taste andappropriate sweetness.

Example 15 Cake

123 g of hen eggs, 45 g of sugar, 345 g of sorbitol liquid, 2.0 g ofsucrose fatty acid ester, 0.35 g of Rebaudioside A or Stevioside wasmixed with 100 g of wheat flour and 200 g of water in order to prepare acake according to a conventional method. The product had an excellenttaste with an optimal sweet flavor.

It is to be understood that the foregoing descriptions and specificembodiments shown herein are merely illustrative of the best mode of theinvention and the principles thereof, and that modifications andadditions may be easily made by those skilled in the art withoutdeparting for the spirit and scope of the invention, which is thereforeunderstood to be limited only by the scope of the appended claims.

1. A low-calorie yoghurt, comprising: a natural sweetener comprisingsweet steviol glycosides with at least 98% of purity, wherein the sweetsteviol glycosides are selected from the group consisting of Steviosidewith at least 98% of purity, and Rebaudioside A with at least 98% ofpurity; defatted milk; and a starter; whereby all components are mixedfor fermentation so as to form the low-calorie yoghurt.
 2. Thelow-calorie yoghurt of claim 1, wherein the Stevioside and RebaudiosideA are purified from Stevia rebaudiana Bertoni in a process comprising:a) drying Stevia rebaudiana leaves; b) treating the dried Steviarebaudiana leaves with water to extract sweet glycosides; c) filteringthe leaves-water mixture to obtain an aqueous filtrate; d) treating theaqueous filtrate with calcium hydroxide or calcium oxide without priortreatment of the aqueous filtrate with an acid to lower the pH of theaqueous filtrate; e) treating the aqueous filtrate with trivalent ironchloride, wherein the aqueous filtrate is neutralized; and f) desalting,decolorizing, and evaporating the extract to dryness to obtain purifiedsweet steviol glycosides with at least 98% of purity.
 3. The low-calorieyoghurt of claim 2, wherein the treating step (b) is performed with awater content of at least 5 to 15 liters per 1 kg of dry leaves, atreating time for 0.5-24 hours, preferably for 1-6 hours, and atemperature range between 25-90° C., preferably between 45-75° C.
 4. Thelow-calorie yoghurt of claim 2, wherein the treating the extract withbase step (d) is performed at a temperature range from 40 to 60° C.,preferably 50 to 55° C., for 0.5-1 hours.
 5. The low-calorie yoghurt ofclaim 2, wherein the process further comprises the following steps: g)dissolving the purified sweet glycosides in alcohol at ambienttemperatures to precipitate Stevioside from solution; h) filtering thesolution from step (g) to recover the precipitate of Stevioside; i)suspending the precipitate of Stevioside obtained in step (h) in analcohol-water solution at 10-12° C. to prepare a high purity Stevioside;and j) recovering the high purity of Stevioside with at least 98% ofpurity.
 6. The low-calorie yoghurt of claim 5, wherein the processfurther comprises: combining remaining alcohol solutions; removing thealcohol; ultrafiltering to obtain a filtrate; and recovering theRebaudioside A with at least 98% of purity.
 7. The low-calorie yoghurtof claim 6, wherein the recovering the Rebaudioside A step comprises:drying the ultrafiltration filtrate; mixing the ultrafiltration filtratewith an alcohol solution; filtering and drying to obtain a driedfiltrate; mixing the dried filtrate with dilute alcohol; and filteringand drying to recover the Rebaudioside A; wherein the mixing with dilutealcohol step is performed with 92% ethanol at 12° C. for 60 minutes. 8.The low-calorie yoghurt of claim 1, further comprising sugar, salt,citric acid, juniper tincture, ascorbic acid, sodium benzoate, coloringincluding orange red color, flavor including vanilla, or fruit juiceselected from the group consisting of orange, apple, lemon, apricot,cherry, and pineapple.
 9. The low-calorie yoghurt of claim 1, whereinthe natural sweetener in the range of 0.01-0.2% (w/w); the defatted milkin the range of 95-99% (w/w); and the starter in the range of 0.05-0.5%(w/w).
 10. A process for producing a low-calorie yoghurt, comprising:admixing defatted milk and a natural sweetener comprising sweet steviolglycosides with at least 98% of purity, wherein the sweet steviolglycosides are selected from the group consisting of Stevioside with atleast 98% of purity, and Rebaudioside A with at least 98% of purity intoa mixture; pasteurizing the mixture and then cooling the mixture; addinga starter into the mixture for fermentation; and optionally addingflavor and coloring into the fermented mixture; whereby produce thelow-calorie yoghurt.
 11. The process of claim 10, wherein the Steviosideand Rebaudioside A are purified from Stevia rebaudiana Bertoni in amethod comprising: a) drying Stevia rebaudiana leaves; b) treating thedried Stevia rebaudiana leaves with water to extract sweet glycosides;c) filtering the leaves-water mixture to obtain an aqueous filtrate; d)treating the aqueous filtrate with calcium hydroxide or calcium oxidewithout prior treatment of the aqueous filtrate with an acid to lowerthe pH of the aqueous filtrate; e) treating the aqueous filtrate withtrivalent iron chloride, wherein the aqueous filtrate is neutralized;and f) desalting, decolorizing, and evaporating the extract to drynessto obtain purified sweet steviol glycosides with at least 98% of purity.12. The process of claim 11, wherein the treating step (b) is performedwith a water content of at least 5 to 15 liters per 1 kg of dry leaves,a treating time for 0.5-24 hours, preferably for 1-6 hours, and atemperature range between 25-90° C., preferably between 45-75° C. 13.The process of claim 11, wherein the treating the extract with base step(d) is performed at a temperature range from 40 to 60° C., preferably 50to 55° C., for 0.5-1 hours.
 14. The process of claim 11, wherein themethod further comprises the following steps: g) dissolving the purifiedsweet glycosides in alcohol at ambient temperatures to precipitateStevioside from solution; h) filtering the solution from step (g) torecover the precipitate of Stevioside; i) suspending the precipitate ofStevioside obtained in step (h) in an alcohol-water solution at 10-12°C. to prepare a high purity Stevioside; and j) recovering the highpurity of Stevioside with at least 98% of purity.
 15. The process ofclaim 14, wherein the method further comprises: combining remainingalcohol solutions; removing the alcohol; ultrafiltering to obtain afiltrate; and recovering the Rebaudioside A with at least 98% of purity.16. The process of claim 15, wherein the recovering the Rebaudioside Astep comprises: drying the ultrafiltration filtrate; mixing theultrafiltration filtrate with an alcohol solution; filtering and dryingto obtain a dried filtrate; mixing the dried filtrate with dilutealcohol; and filtering and drying to recover the Rebaudioside A; whereinthe mixing with dilute alcohol step is performed with 92% ethanol at 12°C. for 60 minutes.
 17. The process of claim 10, wherein the low-calorieyoghurt further comprises sugar, green tea extract, salt, citric acid,juniper tincture, ascorbic acid, sodium benzoate, coloring includingorange red color, flavor including vanilla, or fruit juice selected fromthe group consisting of orange, apple, lemon, apricot, cherry, andpineapple.
 18. The process of claim 10, wherein the natural sweetener inthe range of 0.01-0.2% (w/w); the defatted milk in the range of 95-99%(w/w); and the starter in the range of 0.05-0.5% (w/w).